I mean, even if the effect is significant, it might just come down to the fact that for one person the activity alleviates stress and for the other it does the

I mean, even if the effect is significant, it might just come down to the fact that for one person the activity alleviates stress and for the other it does the opposite. Sure, the physical activity is good for circulation and cardio/strength will vary a lot, but I imagine most of the mood-altering aspects and impact on things like GABA/cortisol/glutamate are largely dependent on whether someone is genuinely enjoying themselves, just ok with it, or find it to be a chore.